400+ TypeScript Interview Questions

Are you preparing for a developer interview and want to master TypeScript? This course is designed to help you tackle TypeScript interview questions with confidence by practicing 300+ multiple choice questions (MCQs) covering beginner to advanced concepts.

Through focused and interactive quizzes, you’ll explore a wide range of topics such as type annotations, interfaces, classes, modules, type inference, and generics. Each question is carefully crafted to test your conceptual understanding and real-world application skills. Detailed explanations accompany every answer, helping you not just choose the right option, but also understand why it's correct.

Whether you're a junior developer entering your first technical interview or an experienced engineer brushing up your TypeScript skills, this course will prepare you to succeed. The course also includes mock interview tests that simulate real-time coding assessments and hiring processes.

You'll gain insights into tricky language features like type narrowing, discriminated unions, and declaration merging. Learn how to read TypeScript code confidently, identify common bugs, and apply best practices effectively.

By the end of this course, you’ll be able to:

• Analyze and solve TypeScript coding problems efficiently.

• Understand and explain TypeScript concepts during interviews.

• Approach interviews with a deeper understanding and increased confidence.

This course serves as a compact, high-impact resource for technical interview prep, skill validation, and rapid TypeScript revision.

Interview Topics Are :-

TypeScript Interview Preparation Guide - Beginner to Advanced

Overview

This comprehensive guide covers 315+ TypeScript concepts across three difficulty levels, designed for developers with 0-10+ years of experience. Each section includes targeted MCQ counts and practical applications.

I. Beginner Level (0-2 Years Experience)

Difficulty: Easy | Total MCQ Count: 90

1. Introduction to TypeScript

MCQ Count: 10

Core Concepts

• What is TypeScript? (Superset of JavaScript, statically typed)

• Why use TypeScript?

  • Benefits: type safety, tooling, readability, maintainability

• How TypeScript compiles to JavaScript (.ts to .js)

• Basic setup and compilation (tsc command, tsconfig.json basics)

2. Basic Types

MCQ Count: 15

Primitive Types

• number, string, boolean, null, undefined, symbol, bigint

• The any type (when to use, pitfalls)

• The void type (for functions that don't return)

• The unknown type (safer alternative to any, requires type assertion)

• Type inference

3. Variables and Type Annotations

MCQ Count: 8

Variable Declaration

• Declaring variables with let, const, var (and their scoping)

• Explicit vs. Implicit type assignment

• Basic type annotations for variables

4. Arrays and Tuples

MCQ Count: 10

Array Types

• Declaring arrays (e.g., number[], Array<string>)

• Tuple types (fixed-size arrays with known types at specific positions)

• Readonly tuples

5. Enums

MCQ Count: 8

Enum Types

• Numeric enums (default behavior, auto-incrementing)

• String enums

• Heterogeneous enums

• Reverse mapping in numeric enums

6. Functions

MCQ Count: 12

Function Types

• Function declaration with type annotations (parameters, return type)

• Optional parameters

• Default parameters

• Rest parameters

• Arrow functions in TypeScript

• Function overloading (basic concept)

7. Interfaces

MCQ Count: 15

Interface Concepts

• Defining object shapes with interfaces

• Optional properties in interfaces

• Readonly properties in interfaces

• Extending interfaces

• Function types in interfaces

• Class implementing interfaces

8. Classes and OOP Basics

MCQ Count: 12

Class Fundamentals

• Class declaration

• Constructors

• Properties and Methods

• Access modifiers (public, private, protected)

• Inheritance (extends keyword)

II. Intermediate Level (3-5 Years Experience)

Difficulty: Medium | Total MCQ Count: 80

9. Union and Intersection Types

MCQ Count: 10

Advanced Type Combinations

• Union types (|) - allowing a value to be one of several types

• Intersection types (&) - combining multiple types into one

• Discriminated unions

10. Type Aliases vs. Interfaces

MCQ Count: 8

Type System Choices

• When to use type vs. interface

• Key differences (declaration merging, type for primitives/unions/intersections)

11. Generics

MCQ Count: 18

Generic Programming

• Introduction to generics (reusable components, type safety)

• Generic functions

• Generic interfaces

• Generic classes

• Generic constraints (extends keyword)

• keyof operator with generics

12. Type Guards and Type Narrowing

MCQ Count: 12

Runtime Type Checking

• typeof type guard

• instanceof type guard

• in operator type guard

• User-defined type guards (predicates)

• Control flow analysis

13. Advanced Class Concepts

MCQ Count: 10

Enhanced OOP Features

• Abstract classes and methods

• Static members

• Readonly modifier for class properties

• Implements clauses with classes

14. Modules

MCQ Count: 10

Module System

• ES Modules (import, export)

• Module resolution strategies (node, classic)

• Default exports vs. Named exports

• Re-exporting

15. tsconfig.json Deep Dive

MCQ Count: 12

Compiler Configuration

• Key compiler options:

  • target, module, strict, noImplicitAny, strictNullChecks

  • esModuleInterop, jsx, outDir, rootDir

• include, exclude, files

• Project references (basic understanding)

III. Advanced Level (6-10 Years Experience)

Difficulty: Hard | Total MCQ Count: 145

16. Mapped Types

MCQ Count: 15

Type Transformation

• Syntax and purpose of mapped types ([P in K])

• Common utility types created with mapped types:

  • Partial<T>, Readonly<T>, Pick<T, K>, Omit<T, K>

• Custom mapped types

• keyof and typeof in conjunction with mapped types

17. Conditional Types

MCQ Count: 20

Advanced Type Logic

• Syntax and logic (T extends U ? X : Y)

• infer keyword (infer R)

• Distributed conditional types

• Common utility types created with conditional types:

  • Exclude<T, U>, Extract<T, U>, NonNullable<T>

  • ReturnType<T>, Parameters<T>

18. Decorators

MCQ Count: 18

Metaprogramming

• Purpose and usage of decorators

• Class decorators

• Method decorators

• Property decorators

• Parameter decorators

• Accessor decorators

• Decorator factories

• Enabling decorators in tsconfig.json

19. Declaration Merging

MCQ Count: 10

Type System Flexibility

• How interfaces merge

• Namespace merging

• Module augmentation (extending existing modules/libraries)

20. Type System Internals & Advanced Concepts

MCQ Count: 25

Deep Type System Understanding

• Structural vs. Nominal Typing (TypeScript's approach)

• Covariance and Contravariance in function arguments and return types

• this types

• as const assertions

• Template Literal Types

• Recursive Conditional Types (for complex data structures)

• Type Predicates vs. Type Assertions (deep dive into differences and use cases)

• satisfies operator (TypeScript 4.9+)

21. Utility Types Deep Dive & Custom Utilities

MCQ Count: 15

Advanced Type Utilities

• In-depth understanding of standard utility types:

  • Required, Record, NonNullable, InstanceType

  • ThisParameterType, OmitThisParameter, Awaited

• Creating custom utility types for specific use cases

22. .d.ts Files and Type Definitions

MCQ Count: 15

Type Declaration System

• Purpose of declaration files (.d.ts)

• Writing declaration files for JavaScript libraries

• declare keyword for ambient declarations

• Global augmentation

• Type package management (@types/)

23. Advanced tsconfig.json & Project Structure

MCQ Count: 12

Enterprise Configuration

• Strict mode options breakdown

• paths and baseUrl for module aliasing

• isolatedModules

• downlevelIteration

• Understanding moduleResolution

• Monorepo considerations with TypeScript project references

24. Compiler API (Conceptual)

MCQ Count: 5

TypeScript Internals

• Understanding that TypeScript is programmable

• Brief overview of what the Compiler API allows:

  • Custom transformers, language services

  • No coding required, just awareness

25. Performance and Best Practices

MCQ Count: 10

Production Optimization

• Optimizing compilation time

• Avoiding any (and when it might be acceptable)

• Code organization and modularity for large-scale TypeScript projects

• Common pitfalls and how to avoid them

• Maintaining type safety in complex scenarios

This structured approach ensures comprehensive coverage of TypeScript concepts, progressing logically from fundamental syntax to advanced type system features. The 315 MCQ potential provides extensive practice opportunities for technical interviews at all levels.